Rotary compressor



June 23, 1936. c BEUST ROTARY COMPRESSOR Filed Nov. 21, 1933 6Sheets-Sheet 1 E18 29mm \hme 1936- c. J.' BEUST I ROTARY COMPRESSORFiled Nov. 21, 1935 6 Sheets-Sheet 2 dbtomwgg June 23, 1936. v c ST2,044,873

ROTARY COMPRES 5 OR gig; 36

"mtg? ,IIIIII mlliziwa 4o c. fIBZuST June 23, 1936. Q BEUST 2,044,873

ROTARY COMPRES S OR Filed NOV. 21, 1935 6 Sheets-Sheet 4 CONDENSERREFRIGERATOR v.

55mm T019 r June 23, 1936. c. J. BEUST ROTARY COMPRESSOR Filed Nov. 21,195:

6 Sheets-Sheet 5 June 23, 1936. C J, BEUST 2,044,873

ROTARY COMPRES SOR Filed Nov. 21, 1933 6 Sheets-Sheet 6 Patented June23, 1936 UNITED STATES PATENT OFFICE 2,044,873 ROTARY COMPRESSOR CecilJ. Beust, Atlanta, Ga.

Application November 21, 1933, Serial No. 699,066

17 Claims. (Cl. 230-205) This invention which is a continuation-in-partof my application Serial No. 641,079, filed November 3, 1932, relates torotary compressors. Its purpose is to provide means for sealing thecompression chambers of such apparatus against leakage of the compressedfluid.

Compressors or pumps employing the very desirable fundamental principleof rotary motion have heretofore enjoyed but a limited field of usefulness on account of their inherent fault of slippage or shortcircuiting of the fluid being pumped or compressed, whereby theirvolumetric effi ciency is low, and the inefficiency increases in directratio to the discharge pressure.

7 New fields have been developed for the employment of fluid pressurepumps or compressors, notably the mechanical refrigeration art, whichcan tolerate no compression leakage whatsoever, and from which newfields the rotary compressor issubstantially barred on account of itsdefeet of inherent compression leakage, despite its otherwise idealmechanical qualifications.

The present invention has for its object the construction of acompressor or pump of any known type in which the chambers arehermetically sealed against leakage by pressures on the outside inexcess of the pressures from within and which outside pressures arederived from pressures within.

A more specific object of the invention is t provide means for sealingthe chambers'of the rotary pump or compressor, the outside area of whichmeans exceeds the aggregate area pressed against from within the pump orcompressor and which sealing means are opposed to the within pressureresponsive to fluid pressure acting upon certain localized areas on theoutside of said sealing means, ordinarily greater than the areas pressedupon from within, but being ordinarily less than the entire outside areaof said sealing means so as to prevent the building up of excessivesealing pressures which might create undesirable or disastrous frictionwith respect to the rotating parts of the pump or compressor.

Inasmuch as those parts of the rotor of the compressor which are subjectto maximum angu lar velocity in the operation of the compressor would bethe most susceptible to the destructive friction created by excesssealing pressure against said portions of the rotor of the pump orcompressor, the invention contemplates the withdrawing of the fluidpressed areas on the outside of said sealing means away from theperipheral region of said sealing means whereby the peripheral portionsof the rotor will be relieved from the maximum value of the sealingpressure.

Another object of the invention is the provision of means for creatingan initial pressure bias upon the outer side of said sealing means mmdering the latter effective until suflicient pressure has been generatedwithin the compressor or pump to supplant the initial pressure creatingmeans.

A further object of the invention is to provide 10 in a compressor ofthe vane type trunnions for taking the end thrust of thevanes when theends of the latter are exposed to the high pressure at the discharge ofthe compressor, without transmitting the said end thrust through therotor itself and to the opposite side thereof.

Still another object of the invention in connection with the trunnionsis the provision of split expansion rings seated on said trunnions, withclearance and abutting expansively against the inner ends of the vaneswhereby they are constantly pressed against the peripheral wall of thepump or compressor with a resilient pressure which at all timescompensates for wear.

Another object of the invention is to provide a compressor in which asingle rotor is arranged to draw a plurality of suction pressures ofdifierent values.

Other objects of the invention will appear as the following descriptionof a preferred and prac- 3 tical embodiment of the invention proceeds.

Although there are probably a number of known types of rotarycompressors or pumps to which the present invention may be applied, ithas been exemplified in the accompanying drawings by illustrating it incombination with two types of compressor.

In the drawings, the same characters of reference have been usedthroughout the several figures to designate identical parts: 40

Figure 1 is a vertical side section, a portion of the rotor of thecompressor being shown in elevation;

Figure 2 is asection taken along the line 22 of Figure 1;

Figure 3 is a detail taken in a plane perpendicular to the axis ofrotation of the compressor illustrating the relation of the expansionring to the trunnion and to the vanes;

Figure 4 is a section taken along the line 4-4 of Figure 3;

Figure 5 is a horizontal section through the compressor, part beingomitted;

Figure 6 is a. section taken along the line 6-6 of Figure 1; 5

I so

Figure '7 is a detail in section taken along the line 1-1 of Figure 6;

Figure 8 is a perspective view of the flexible cupped members or pistonsby means of which Scaling pressure is applied to the sealing ring;

Figure 9 .is a perspective view of the sealing ring partly in section;

Figure 10 is a section takenalong the line Ill-400i Figure 9;

Figure 11 is a view in detail showing the un--.

restrained cross-sectional shape of any one of the cupped members orpistons and illustrating the manner in which it is seated within therecesses in the head.

Figure 12 is a view in detail showing the construction of the packingfor the outer shoes of the vanes;

Figure 13 is a diagrammatic representation of the lubricant circulation;

Figures 14 and 15 are respectively, vertical sections through analternative form of compresso taken in perpendicular planes;

Figure 16 is a perspective view of the sealing in Figures Hand 15.; I 7

Figures 17 and 18 are respectively, sections taken along the linesil--Il and l 8l8 of Fig.- ure'16; an'd'T.

ring employed in that form of the inventionshown Figures 19 and 20 arerespectively, an exploded perspective. view and; a section view through'a modified form ofshoe-construction.

Figure -21 is a detail of an alternative construetion to that shown inFigure 5.

Referringfnow in detail to'the several figures and first :adverting tothat'form of the inven-- tion shown inFigures 1' and 2, the compressorcomprises astator whichincludes-a support I and a casing in generaldesignated by the reference character 2 and comprising a generallycylindrical portion'3 and end heads 4 and 5 suitablyls ecured to theperipheral portion." The inner wall 6 of the peripheral portion iscylindrical. Airo tor I is mounted withinthe space enclosed' be- Y tweenthe peripheral portion of the casing'and the heads, said rotor beingmounted upon arr-axis 8 which is eccentric to the "axis of theperipheral wall of the stator. The diameter of the rotor is such that itmakes contact with the inner'peripheral wall of the casing, preferablyat the lower side of the compressor.- In order that the region ofcontact between the rotor and stator may be more than a line oftangency, theinner peripheral "'wall of the rotor, is throughlan'appreciable arc; machined to a curvature corresponding to that'oftherotor and forming'a'se'at for the motor which will hereinafter'be'referred to as the arc 'of expulsion. The rotor is [formedwithradial slots; 9 extendingithere=across and op'ening intheenclsof saidrotor.- Sliding vanes 'lllaremountedin the slots of said rotorextendinggthere-acros s' and terminating in planes flush with theends'iof 'saidrot'or. At opposite ends 1 'therotor is formed withcircular recesses ll, see

eccentricity, of "the rotor. 7 acts not only 9.52, wearcompensating'means for ferring to Figure l the wall of the recessapproaches very close to the trunnion adjacent the point l5, but extendsquite a distance below said trunnion as shown at IS in the same figure.The slots 9 which serve as guideways for the vanes open into thecylindrical walls of the recesses l I. Expansiblemetallic split rings l1and I8 are mounted with clearance on the ends of the trunnions whichextend within the recesses ll. Figure 4 shows that the rings H are splitdiagonally widthwise as indicated at IS in Figure 4. The

lower ends of the vanes are provided with a concave semi-cylindricalseat 20 extending thereacross and within said seat a shoe is freelymountved, said shoe having a convex surface matching the concave seat.The working faces of the shoes 2| are concave and the split rings I1 andI8 are expanded outwardly against said shoes, keeping the vanes inintimate contact with the inner peripheral wall of the stator.

On account of the clearance between the split rings and the trunnions,and the frictional presof the bottoms of the vanes against the splitrings through an amplitude equal to twice the The ring therefore thevanes; but also asa wear piece to minimize the wear between the shoes 2|and the ring itself. The primary function of the ring and trunnionconstruction however is to afford a rigid abutment for receiving the endthrust due to the pressure of the compressed fluid against the ends ofthe vaneswhen the latter become exposed during their period of transitacross the discharge port, best shown in Figure 2. In the absence ofsome fixed abutment such as the trunnions, such end thrust reactsagainst the rings forcing the rings themselves toward the diametricalopposite side of thestator and pushing the ends of the opposite vanesagainst the inner peripheral wall of the casing with excessive anddestructive pressure.

The upper ends of the vanes are provided with shoe pieces 23 similar tothe shoes at the inner ends of the vanes excepting that their workingfaces are convex corresponding to the curvature of the inner peripheralwall of the casing.

Figure 2 shows that there is a suction port 24 opening at a point 25adjacent one end of the arc of expulsion and circumscribing the spacesbetween several of the vanes. On the opposite side of the compressor isa discharge port 26 circumscribing an are somewhat less than thedistance between the two vanes and adjacent the opposite end of the arcof expulsion. The space between the rotor and stator on opposite sidesof the diametrical line which passes through the middle of the arc ofexpulsion defines respectively suction and compression chambers. Figure2 shows a secondary suction port which will be referred to later.

I In that form of the invention illustrated in Figures 1 and 2, thecylindrical portion of the (casing is jacketed as indicated at 28 overthat area which circumscribes the compression chamher, the coolingmedium being preferably'oil which is admitted by way of the pipe 29 andexited through a discharge conduit 30. This oil has already-come throughthe interior parts of the compressor as will be later explained and isin general warmer than the fluid admitted to the compressor on thesution side although its temperature is cooler than the compressedfluid.

Therefore, while the oil is useful in cooling the compression chamber,it is in general preferable to restrict it in such manner that it shallnot raise the temperature of the inducted fluid.

In the compressor of the type illustrated the leakage which reduces thevolumetric efficiency generally occurs at four places, between the rotorand. stator in the arc of expulsion, around the ends of the rotor andvanes, between the ends of the vanes and the inner peripheral wall ofthe cylinder, and about the vanes in their guideways. Various means havebeen devised for sealing these points of leakage, and the presentinvention oflfers nothing new with respect to sealing the joint alongthe expulsion arc. However, the invention does propose an improved andvery versatile means for sealing the compressor against leakage aroundthe sides of the vanes, over the tops 01' the vanes and back of thevanes by impressing upon the sealing instrumentalities predominantpressures derived from pressures within the compressor itself.

In my application for patent of which the present is a continuingapplication, is disclosed a sealing ring forming an end wall for thecompression and suction chambers and a piston on the outside of saidsealing ring and co-extensive with the area thereof with meansforapplying the high pressure of the compressor discharge to the rear ofthis piston for biasing the sealing ring in opposition to the pressureswithin the suction and compression chambers.

In practice it was found that this sealing pressure was ordinarily soexcessive as to produce unnecessary friction stresses between the endsof the rotor and vanes and the sealing ring which made it difficult torotate the rotor and furthermore led to rapid wear of the engagingparts.

The invention as embodied in the present continuing application includesthe sealing ring 3| seated in a suitable recess in the head and havingits outer peripheral edge co-incident with the inner peripheralcylindrical Wall of the casing. The width of the sealing ring is suchthat it extends substantially to the bases of the v'anes Ill. Thesealing ring 3| rests against the sides of the vanes and the interveningportions of the rotor. It is normally, in the initial state of reposeof.

the compressor, kept thus pressed by a plurality of small springs 32seated in recesses 33 in the head 4 and pressing outwardly against saidring. These springs are of course totally inadequate to maintain asealing pressure after the pressures within the compressor build up, butthey merely prevent leakage when the compressor first starts and whenthere is very little differential between inside and outside pressures.

In order to avoid the excessive endwise thrust against the rotatingparts of the compressor which the imposition of discharged pressure overthe whole outer face of the sealing ring engenders and as covered in theparent application, the present invention contemplates in its broadestaspect segregating the portions of the area of the outer side of thesealing ring which lie opposite the compression and suction chambers,and applying to those segregate areas pressures from within thecompressor proportional to the pressures to be sealed in. For example,high discharge pressure would be imposed upon that part of the ringopposite the compression chamber, and

suction pressure against that part of the ring which overlies thesuction chamber, it being understood of course that the outside area ofthe sealing ring is at all times greater than the inside surface of saidring pressed upon by the within pressures since part of tne inside areaof the ring is occluded by the sides of the vanes and by the interveningend portions of the rotor. It is also to be understood that the areas ofthe outer surface of the ring respectively impressed with 10 thedischarge pressure and the suction pressure are always in excess of thepressures to be sealed and it is therefore quite feasible to use a lowerpressure value on the outside of said ring to seal a higher pressurewithin. 15

A third pressure is available Within the compressor. A certain amount ofinternal leakage is inevitable from the high to the low side of thecompressor around one or another of the relatively moving parts so thatin the oil spaces with-- 20 in the central portion of the compressorthere is a pressure value which is a mean between the high pressure ofthe compression chamber and the low pressure of the suction chamber.

In the preferred embodiment of my invention this intermediate pressuremay be employed.

In order to segregate the high and low pressure areas on the outside ofthe sealing ring, the adjacent head 4 is provided with recesses 34 ofmore or less crescent shape corresponding to the shapes of the chambersopposite which they lie, the cusps 36 and 3l'of said recesses beingadjacent the are of expulsion. Since it will in general be necessary toseal the joint along said are of expulsion against leakage a thirdrecess 38 is provided at this point. Pistons are arranged in saidrecesses. The pistons may be of any suitable construction, but in thepresent embodiment of the invention they consist of flexible cuppedrubber members 39, 40 and 4| having side flanges 42 and 43 terminatingin feather edges 44. Figure 11 shows that in their unconfined state, theflanges of the cupped members flare slightly and the bottom 45 bulgesslightly outward. Said cupped members are crowded into the respectiverecesses in inverted position in the manner indicated in the lower halfof Figure 11 so that there is an inherent pressure of the flanges 43against the corresponding walls of the recesses. The spaces enclosedbeneath the cupped members or pistons 5 39, 40 and 4| form pressurechambers adapted to be placed in communication by suitable conduits withsources of compression within the compressor. When the pistons 39, 49and 4| are in place, the slightly bulged bottoms of said pistons pressagainst corresponding areas of the sealing ring.

Figure 5 shows that the discharge port 26 is connected by a system ofconduits 46 suitably bored through the casing to the pressure chamberback of the piston 39. Instead of making use of the suction pressure toactivate the piston 40 which presses that part of the sealing ringopposite the suction chamber, the intermediate pressure is employed andconsequently Figure 5 5 does not show the suction port communicatingwith the pressure chamber behind the piston 49. By reference to Figure 1however, it will be observed that the space 3 between the trunnion androtor and in which this intermediate pressure builds up, is connected byconduits 41, 48 and 49 with the pressure chamber back of the piston 46.The piston 4| which overlies that part of the ring opposite the jointalong the expulsion arc is actuated in response to the intermediatepressure de- 7| rived from one of the oil passages 50 by way of aconduit 5| best shown in Figure 6.

If it were desired to use the suction pressure instead of theintermediate pressure to seal the suction chamber, the latter chamberwould be tapped into the back of the piston 40, in a similar manner tothat illustrated in connection with the leading of the dischargepressure to the back of the piston 39.

It has been stated that initial sealing contact between the sealing ringand the sides of the vanes and rotor is normally accomplished by meansof the springs 32. As an alternative or an auxiliary to the springs 32,fluid pressure means may be employed for maintaining this initialsealing relationship of the parts. With this object in view, the suctionport is tapped by means of a conduit 52 leading to the back of that partof the sealing area not contacted by the pistons 39, 4|] and 4 When thecompressor first starts, the pressure behind the several pistons is nilor at least not greater than the pressures within the compressor. Thearea subjected to these pressures is however temporarily augmented bypressure-from the suction port being applied as indicated to the area ofthe sealing ring not affected by the pistons. Thus the entire outsidearea of the sealing ring is pressed by a pressure which may be not inexcess of the pressure within the compressor, nevertheless, since theoutside area is greater than the inside area, the aggregate area on theoutside exceeds that on the inside of the compressor and the sealingring is initially biased in a sealing direction.

Figure 5 shows the conduit 52 controlled by an adjustable needle valye'5'3 which is not intended to be frequently adjusted, but merely oncefor all, according to the amount of auxiliary pressure which may berequired in addition to the springs 32 or in the absence of such springsaccording to the amount of pressure necessitated to effect the properinitial sealing of the sealing ring.

The provision of the localized areas of differential pressure on theoutside of the sealing ring, and the pistons by means of which thisdifferential pressure is applied, constitutes an extremely versatilearrangement permitting the said localized areas to be modified orshifted in designing various compressors, according to their size, thespeed at which they are to be operated and the pressures which they arecalled upon to produce. For example, it has been found, particularlywith-large sized compressors, that the angular velocity of the tips ofthe vanes gives rise to a condition of destructive friction when thesides of the tips of the vanes are excessively pressed particularly whenthe compressor is compressing to high pressures. In designing suchcompressors, it becomes necessary merely to remove the localized areasaway from the peripheral region of said vanes, while still maintainingan extent of their area which insures that a predominant pressure willbe applied to the outer side of the sealing ring. The tips of the vanesare thus relieved from excess pressures while at the same time thenecessary sealing pressures are maintained.

It will be understood with reference to this ,phase of the inventionthat while the sealing means above described may be applied separatelyto both sides of the compressor, it is deemed necessary in general onlyto apply the sealing ring to one side, since the pressure of the pistonsagainst said sealing ring is transmitted to the rotor and vanes, pushingthem bodily over into contact with the machined surface of the oppositehead.

Leakage from the chambers of the compressor around the peripheral facesof the sealing ring 3| is prevented by means of continuous flexiblepiston packings 54 and 55 seated in inverted portion in channels 56 and51 formed in the said peripheral walls of said sealing ring. The facesof said pistons make contact with the adjacent side walls of therecesses in said head in which said piston packings are mounted. Thespaces enclosed behind said piston packings are placed in communicationwith suitable sources of pressure from within the compressor. Since thejoints which these piston packings seal are fixed except for a veryslight range of sliding movement in a direction parallel to the axis ofthe rotor, the problem of nicely egulating the sealing pressure toprevent undue frictional wear or resistance is lacking. However it is astep in the nature of good engineering to employ a sealing pressurewhich is not grossly in excess of the sealing needs. Therefore, while itis quite within the range of the invention to utilize the dischargepressure of the compressor for projecting these piston packings againstthe walls with which they react, it is preferred to employ theintermediate pressure from the interior of the compressor between thesuction and compression chambers. This is accomplished by providinggrooves 58 and 59 in the outer face of the sealing ring, the groove 58,shown in Figure 1, being in communication with oil conduits 60 extendingtransversely through the rotor and the contents-\of which conduits areunder the desired intermediate pressure through various minute leakagesources between the compression chamber and the suction chamber of thecompressor, while the groove 59 derives its pressure from the interiordisplacement space on the discharge side.

The grooves 59 are shown in duplicate and spaced apart a distance equalat least to the width of one of the vanes, for the simple reason thatsince theyare shown as being radially directed, they are'occluded byeach vane in the course of its rotation. If there were only one groove58 there would be a periodic cutting off of the pressure from the pistonpacking 55. Since the two grooves are spaced apart a distance equal atleast to the width of the vanes both can never be occluded at the sametime and consequently the pressure behind the piston packing 55 isuninterrupted.

Referring now-to Figures 2, 3 and 4, and Figures 12, 19 and 20v showingdetails, attention is directed to the means for preventing the shortcircuiting of the compression pressure around the vanes. Figures 2, 3and 4 show that the vanes ID are each provided with a shoe 2| at itslower end and a shoe piece 23 at its upper end, the shoes and shoepieces being oscillatably seated in concave cylindrical seats in theends of said vanes. The shoes 2| which bear against the split ring I!merely act as wear pieces and to keep the entire ends of the vanes incontact with the split ring instead of a mere line of contact as wouldnormally be the case due to the canting of the vanes relative to thesplit ring on account of the eccentricity of the rotor relative to thetrunnions. Wear between the inner ends of the vanes and the split ringis thus distributed over the whole area of the shoe instead of beingconcentrated along a mere line of contact. The shoes 2| are notparticularly concerned with sealing with the adjacent parts againstpressure leakage for this is taken care of in connection with thepacking of the vanes and the upper shoe pieces.

Figure 12 shows that the rotor is provided both in front; of andrearwardly thereof with reference to its direction of rotation withchannels 6| and 62 in which are seated wear pieces 63 and 64 extendingwidthwise the full length of the rotor and flush with the rotor andvanes, said wear pieces being packed by flexible pistons 65 and 66hermetically fitting the channels in which they lie and being in generalof the same construction as the flexible pistons 39, 40 and 4| and thepiston packings 54 and 55. The spaces enclosed within said channels bythe respective pistons form pressure chambers, the chamber on theadvance side of the vane being in communication with the compressionchamber by means of a bore 61 while the chamber on the trailing side ofthe vane is in communication by way of a bore 64" with the space in therotor back of the vane III which space is under the intermediatepressure of the compressor said pressure being transmitted through theends of the vane slots which open as shown in Figure 2 into a space inthe middle of the end plate, which space receives inevitable pressureleakage from both the compression and suction chambers and is alsosubject to the pressure of the lubrication system. Thus each side of thevane is sealed against leakage by a pressure superior to that which itopposes.

Figure 12 shows also that the shoe piece 23 is biased actively outwardagainst the inner peripheral wall of the casing of the stator by a wearpiece 68 positioned at the open end of a channel 69 formed in the vanebeneath said shoe piece,

and backed by a flexible piston 10 subject to pressure within thechamber H derived by way of the conduit 12 from the high compressionside of the vane l0.

The shoe piece 23 shown in Figure 12 and illustrated in the preferredembodiment of the invention is symmetrical in cross section. A modifiedform of the invention is shown in Figures 19 and 20 in which the shoe isof asymmetrical cross section, the predominant portion 13 of whichextends into the high compression chamber and presenting a broad ledgeor shoulder I4 to the pressure in said chamber through which medium itis canted into firm frictional contact with the inner peripheral wall ofthe casing. The

shoe in this form of the invention is shown as provided with a separableand therefore replaceable wear piece I5 grooved as at 16 to receive anysuitable form of packing strips 11.

In this form of the invention the shoe piece is provided with acylindrical channel 18 having a cross section greater than asemi-circle, and receives a correspondingly shaped bead 19 formed on theend of the vane, said shoe being irremovable radia ly, but readilyremovable for replacement by sliding it in a transverse direction afterthe rotor has been removed from the casing. The joint between the shoeand the end of the vane is packed in a manner similar with that shown inconnection with the form of the invention exemplified in Figure 12, awear piece being provided in a channel 8| formed in the shoe, said wearpiece abutting the surface of the bead l9 and being backed by a flexiblepiston 82 in communication with the pressure of the compression chamberby way of a bore 83.

In connection with the packings on the advance and trailing s des of thevanes and in as sociation with the joints between the outer shoe piecesand the vanes, light sinuous springs 84 are placed behind the flexiblepistons to impart initial sealing pressure to said pistons before thecompressor upon starting has had the opportunity to generate the normaleffective pressures.

It will be understood, in contemplating the operation of the compressorthat all of the interstices between the various parts excluding ofcourse the suction and compression chambers are filed with oil and thatthe fluid pressure impressed upon the various pistons is transmitted bythe medium of oil. This oil is circulated by a pump 85 to the jacket 28,see Figure 13. From the jacket it flows to a suitable cooler 85 fromwhich it is conducted by a conduit 81 to an oil chamber 88 adjacent thebearing on one side, see Figure 1, from which it flows through thebearing and through a series of conduits 60 in the rotor, through aseries of oil passages 50 in the boss 89 of the head 4 which supportsthe trunnion l3, through the opposite bearing and again to the pump byway of a passage 90.

A certain amount of oil necessarily-finds its way into the suction orcompression chambers mixing with the fluid to be compressed, the oil andcompressed fluid being conducted to a sep aratorll, see again Figure 13,and in the case to draw two distinct suction pressures by one end of thesame compressor. This may be ac complished in the present invention byproviding the primary and secondary suction or induction ports 24 and 21respectively. The primary suction port communicates with the suctionchamber at the advance end thereof and therefore pulls the lowestpressure. By the time the suction chamber has rotated to the point atwhich it communicates with the secondary induction portion it is alreadyoccupied with fluid taken in at the primary induction portion so that itis capable of drawing upon the secondary induction port with a higherpressure value. The primary induction port may lead from a coil at a lowice making temperature 15 F., while the secondary induction port maylead from a coil at a higher temperature such for example as is suitablefor keeping an ice storage room at or just before freezing, 28-32 F.

Referring now to that form of the invention illustrated in Figures 14,15 and 16, a compressor of the gear type is illustrated, the rotorcomprising two meshing gear impellors operating within a chamber formedby a casing having a cylindrical peripheral portion 91 and closed byheads 98 and 99. The problem of sealing insofar as it is generic to thisform of the invention and previously described is confined to the endseal I00 shown at the left of the rotor elements in Figure 14 and whichis similar in construction and in mode of operation to the firstdescribed form of the invention excepting of course that its shape ismodified in accordance with the shape of the rotor chamber, the sealingring being illustrated in Figure 16 and being in the form of a figure 8.The head 98 between which and the rotor elements the sealing ring Hillis placed is provided with suitably located recesses in which theflexible cupped pistons l0l and I02 are seated.

compression chamber between the gears while the piston I 02 is muchlarger, following the shape of the suction and transfer chambers of thecompressor. In position, extent and construction, these pistons followthe same principles as do corresponding parts of that form of theinvention shown in Figures 1 and 2. Figure 14 shows that the piston llilwhich seals the compression chamber derives its opposing pressure fromthe discharge chamber of the compressor while the piston I02 is incommunication with suction pressure derived from the interior of thecompressor through a conduit I03. The peripheral edges of the sealingring Hill are provided with channels and endless piston packings seatedtherein in the same manner as is illustrated in connection with thepreferred form of the invention. Figure 16 shows that these peripheralpacking pistonsjeceive their operating pressure byway of grooves I04formed on that face of the sealing ring which is adjacent the interiorof the compressor.

It will be understood that the specific means for sealing against thevarious phases of leakage as described and illustrated in the foregoingdisclosure are merely illustrative and by no means to be construed aslimiting the scope of the invention, which includes broadly all novelequivalent constructions for accomplishing the new and advantageousresults as herein set forth.

What I claim is:

1. Rotary compressor comprising a casing, a rotor withinsaid casing,said rotor co-operating with the inner peripheral wall of said casingand with suitable end wall structure to form suction and compressionchambers, including a sealing member forming an end wall for at leastone side of said suction and compression chambers making endwise contactwith said rotor whereby the area of said end wall exposed to pressurewithin said chambers is less than the entire area of the outer side ofsaid end wall, means for pressing said end wall against said rotor byexternally applied fluid pressures derived from pressures within saidcompressor, and means for restricting the application of said derivedpressures to areas on the outer side of said end wall remote from theouter peripheral portion thereof for relieving the peripheral portionsof the rotor, that is to say, those parts having maximum angularvelocity, from excess endwise friction, said restricting meanscomprising ahead between which and the side of the rotor said end wallis positioned, said'head having recesses opening in the face thereof,the open sides of which delineate the said areas, flexible cuppedmembers hermetically fitting said recesses and forming therewithpressure chambers, the bot toms of said cupped members contacting saidend wall and the derived pressures being in communication with saidpressure chambers, the extent of said areas being sufliciently less thanthe entire area of the outer side of said end wall to avoid excessivesealing pressure but sufficiently great to oppose a predominant pressureto the pressure within said chambers.

2. Rotary compressor comprising a casing, a rotor within said casing andeccentrically mounted with respect to the interior peripheral wall ofsaid casing so as to contact the latter through an appreciable arc,vanes slidably guided by said rotor engaging the peripheral wall of saidcasing and terminating flush with the ends of said rotor, said rotor,vanes, the inner peripheral wall of said casing and suitable end wallstructure co-operating to form suction and compression chambers onopposite sides of said arc, including a sealing member forming an endwall for at least one side of said suction and compression chambersmaking endwise contact with said rotor and said vanes whereby the areaof said end wall exposed to pressure within said chambers is less thanthe entire area of the outer side of said end wall, means for pressingsaid end wall against said rotor and vanes by externally applied fluidpressure derived from pressures within said compressor, and meansfor.restricting the application of said derived pressures to areas onthe outer side of said end wall remote from the outer peripheral portionthereof for relieving the peripheral portions of said vanes, that is tosay, those parts having maximum angular velocity from excess endwisefriction, said restricting means comprising'a head between which and theside of the rotor said end wall is positioned, said head having recessesopening in the face thereof, opposite the chambers to be sealed, theopen sides of which delineate the said areas, flexible cupped membershermetically fitting said recesses and forming therewith pressurechambers, the bottoms of said cupped members contacting said end walland the derived pressures being in communication with said pressurechambers, the extent of said areas being sufficiently less than theentire area of the outer side of said end wall to avoid excessivesealing pressure, but sufliciently great to oppose predominant pressuresto the pressures within said chambers.

3. Rotary compressor comprising a casing, a rotor within said casingeccentrically mounted with respect to the interior peripheral wall ofsaid casing so as to contact the latter throughout an appreciable arc,vanes slidably guided by said rotor engaging the inner peripheral wallof said casing, said vanes, rotor, the inner peripheral wall of saidcasing combining with suitable end wall structure to form suction andcompression chambers, on opposite sides of said arc, including a sealingmember forming an end wall for at least one side of said suction andcompression chambers making endwise contact with said rotor and saidvanes whereby the area of said end wall exposed to pressure within saidchambers is less than the entire areas of the outer side of said endwall, means for pressing said end wall against said vanes and rotor byexternally applied fluid pressures derived from pressures within saidcompressor at values proportional to the pressures to be sealed, andmeans for restricting the application of said derived pressures to areason the outer side of said end wall remote from the outer peripheralportion thereof for relieving the peripheral portions of the vanes, thatis to say, those parts having maximum angular velocity, from excessendwise friction, said restricting means comprising a head between whichand the side of the rotor and vanes said end wall is positioned, saidhead having recesses opening in the face thereof opposite the chambersto be sealed and opposite said are of contact, the open sides of whichrecesses delineate the said areas, flexible cupped members hermeticallyfitting said recesses and forming therewith pressure chamberathe bottomsof said cupped members contacting said end wall and the derived pressurebeing in communication with said pressure chambers, the extent of saidareas being sufliciently less than the entire area of the outer side ofsaid end wall to avoid excessive sealing pressure, but suflicientlygreat to oppose predominant pressures to the pressures within saidchambers. I

compressor as claimed in claim 3, the

cupped member opposite said are of contact derotor co-operating with theinner peripheral wall of said casing and withsaid head to form suctionand compression chambers, including a sealing member forming an end wallfor at least one side of said suc. ion and compression chambers, fittingwithin the chamber of said casing against the.

inner peripheral wall of said casing on the one hand and upon aportionof said head on the other, said end wall making endwise contactwith said rotor whereby the area of said end wall exposed to pressureswithin said chambers is less than the entire area of the outer side ofsaid end wall, the edges of said end wall which abut the peripheral wallof said casing and said rotor being formed with channels, endlessflexible channeled 7 members seating within the channels of said endwall with their flanges in hermetic elation to 'the sides of saidchannels and their bottoms engaging respectively the inner peripheralwall of said casing and said head, the channels in said end wall andsaid flexible members forming pressure chambers communicating withsources of pressure within said compressor, means for pressing said endwall against said rotor by externally applied fluid pressures derivedfrom pressures within said compressor, and means for restricting theapplication of said derived pressures to localized areas on the outerside of said end wall,

recesses in said head opening in the face thereof,

pistons hermetically fitting said recesses and forming therewithpressure chambers, the bottoms of said pistons contacting said end wallin surfaces defining said areas and the derived pres sures being incommunication with said pressure chambers, the extent of said areasbeing sufliciently less than the entire area of the outer side of saidend wall to avoid excessive sealing pressure, but sufliciently great tooppose predominant pressures to the pressures within said chambers.

6. Rotary compressor comprising a casing, a,

rotor within said casing, said rotor co-operating with the innerperipheral wall of said casing and with suitable end wall structure toform suction and compression chambers, including a sealing memberforming an end wall for at least one side of said suction andcompression chambers making endwise contact with said'rotor whereby thearea of said end wall exposed to pressure within said chambers is lessthan the entire area of the outer side of said end wall, means forpressing said end wall against said rotor by externally applied fluidpressures derived from pressures within said compressor having valuesproportional to the pressures. to be opposed, means for restricting theapplication of said derived pressures to I areas on the outer side ofsaid end wall opposite the respective chambers to be sealed, remote fromthe outer peripheral portion thereof for relieving ity, from excessendwise friction, the extent of said areas being sufliciently less thanthe entire area of the outer side of said end wall to avoid excessivesealing pressure, but sufllciently great to oppose a predominantpressure to the pressures within said chambers, and means for impartingan initial sealing bias to said end wall comprising a conduit leadingfrom a source of pressure within said compressor to the outer side ofsaid end wall outside of said restricted areas. j

'7. Rotary compressor comprising a casing, a rotor within said casingand eccentrically mounted with respect to the interior peripheral wallof said casing so as to contact the latter through an appreciable arc,vanes slidably guided by said rotor engaging the peripheral wall of saidcasing and terminating flush with the ends of said rotor, said rotor,vanes, the inner peripheral wall of said casing and suitable end wallstructureco-operatingto form suction and com-,

pression chambers on opposite sides of said are,

including a sealing member forming an end wallfor at least one side ofsaid suction and compression chambers making endwise contact with saidrotor and said vanes whereby the area of said end wall exposed topressure within said chambers is less than the entire area of the outerside of said end wall, means for passing said end wall against saidrotor and vanes by externally applied fluid pressure derived frompressures within said compressor, means for restricting the applicationof said derived pressuresto areas on the outer side of said end wallremote from the outer peripheral portion. thereof for relieving theperipheral portions of said vanes, that is to say, those parts havingmaximum angular velocity-from excess endwise friction, said restrictingmeans comprising a head between which and the side of the rotor said endwall is positioned, said head having recesses opening in the facethereof, opposite the chambers to be sealed, the open sides of whichdelineate the said areas, flexible cupped members hermetically fittingsaid recesses and forming therewith pressure chambers, the bottoms ofsaid cupped members contacting said end wall and the derived pressuresbeing in communication with said pressure chambers. the extent of saidareas being sufllciently less than the entire area of the outer side ofsaid end wall to avoid excessive sealing pressure, but suflicientlygreat to oppose predominant pressures to the pressures within saidchambers, andmeans for imparting an initial sealing bias to said endwall comprising a conduit leading from a source of pressure within saidcompressor to the outer side of said end wall outside of said restrictedareas. 7

8. Rotary compressor comprising a casing, a rotor within said casing,said rotor co-operating with the inner peripheral wall of said casingand with suitable end wall structure to form suction and compressionchambers, including a sealing member forming an end wall for at leastone side of said suction and compression chambers mak-' -ing theapplication ofsad derived pressures to localized areas on the outer sideof said end wall, said means comprising a head between which and theside of the rotor said end wall is positioned, said head having recessesopening in the face thereof, pistons hermetically fitting said recesses,the bottoms of said pistons contacting said end wall on surfaces whichdelineate said areas, being biased thereagainst by said derivedpressures, the

extent of said areas being sufliciently less ,than the entire area ofthe entire outer wall to avoid excessive sealing pressure butsufficiently great to oppose predominant pressure to the pressure withinsaid chambers.

9. In combination with arotary compressor comprising a casing and arotor therein, defining between them'a chamber, the rotor being eccenetrically mounted on a shaft coaxial with the cir-IJ cumferential wall ofsaid casing, said rotor being; a I 7 -extent of said areasto whichpressure is applied being s'uflicientlyless than the entire area of theformed with radial guideways, and sliding varies in said guidewaysprojectable into said chamber" and bearing against theperipheral wall ofsaid casing, means for sealing said vanes against pressure leakagebetween themselves and said guideways, comprising a channel opening inthe joint between said varies and guideways, a sealing element in saidchannel to close said joint, and means for placing the space within saidchannel behind said sealing element in communication with said chamber.

' 10. In combination with a rotary compressor, comprising a casing and arotor therein, defining between them a chamber, the rotor beingeccentrically mounted on a shaft coaxial with the circumferential wallof said casing, said rotor being formed with radial guideways, andsliding vanes in said guideways projectable into said chamber andbearing against the peripheral wall of said chamber, said vanesseparating said chamber into parts having differential pressures onopposite sides of said vanes, means for admitting fluid under dominantpressure derived from the discharge pressure of the compressor to theinner ends of the guideways behind said vanes, said rotor being formedwith channels opening in the joints between each vane and its guidewayon opposite sides of the said vanes, packing members in said channelsextending through the width of said vanes and bearing against said vanesto close said joints, means for placing the space within the channelbehind the packing on the advance side of-said vane into communicationwith the part of the first named chamber in advance of said vanes, andmeans for placing the space within the channel behind the packing on thetrailing side of said vane into communication with fluid under pressurebehind said vanes.

11. Rotary compressor comprising a casing, a rotor within said casing,said rotor cooperating with the inner peripheral wall of said casing andwith suitable end wall structure to form suction and compressionchambers, including a sealing member forming an end wall for at leastone side of said suction and compression chambers, making an endwisecontact with said rotor whereby the area of said end wall exposed topressure within said chambers is less than the entire area of the outerside of the said end wall, means for pressing said end wall against saidrotor by exi ternally applied fluid pressures derived from pressureswithin said compressor, said pressure applying means having an area ofcontact with the ing endwise contact with said rotor whereby the area ofsaid end wall exposed to pressure within said chambers is less than theentire area of the outer side of said end wall, means for pressing,

to the internal pressure of said compressor, the

outer side of said end wall to avoid excessive, sealing pressure butsuflficiently great to oppose a predominant pressure to the pressureswithin said chambers.

13. In a compressor including a casing and a rotor within the casing, asealing ring within the casing abutting an end of the rotor and formingan end wall of the compression and suction chambers of the compressor,said ring having a peripheral channel, a sealing piston seated in saidchannel forming a movable wall of the pressure chambers defined by thewalls of said channel and the said sealing piston, co-acting with theperipheral wall of said casing, said pressure chamber being incommunication with an internal pressure of the compressor.

14. In a compressor including a casing and a rotor within the casing,- asealing ring within said casing abutting an end of the rotor and formingthe end wall of the compression and suction chambers of the compressor,the outer peripheral face of said ring cooperating sealingly with theperipheral wall of said casing, said ring having an inner peripheralface adapted to coact with the outer surface of a boss extendinginwardly from said casing, said inner and outer peripheral faces beingformed with channels, sealing pistons seated in said channels formingmovable walls of the pressure chambers defined with the peripheral wallof said casing and the outer surface of said boss, said pressurechambers being in communication with an internal pressure of thecompressor.

15. In a compressor including a casing and a rotor within the casing, asealing ring within said casing abutting an end of the rotor and formingthe end wall of the compression and suction chambers of the compressor,the outer peripheral face of saidring cooperating sealingly with theperipheral wall of said casing, said ring having an inner peripheralface adapted to co-act With'the outer surface of a boss extendinginwardly from said casing, said inner and outer peripheralfaces beingformed with channels, sealing {pistons seated in said channels formingmovable walls of the pressure chambers defined between the walls of saidchannels and said seal- Jing pistons, said pistons co-actingrespectively with the peripheral wall of said casing and the .outersurface of said boss, said pressure chambers being in communication withsources of pressures within the compressor proportional to the pressuresagainst which they are opposed.

l6. Rotary compressor comprising a casing, a rotor therein, said rotorcooperating with the inner peripheral wall of said casing and withsuitable end wall structure to.form suction and v compression chambers,including a sealing ring forming an end wall for at least one side ofsaid suction and compression chambers, making endwise contact with saidrotor, means for pressing said end wall against said rotor by fluidpressures derived from pressures within said compressor and havingvalues proportional to the pressures to be opposed, the said meansrestricting said pressures to segregated areas of said wall, saidsealing ring having a peripheral channel, a sealing piston seated insaid channel forming a movable wall or the pressure chamber defined bythe walls of said channel and said sealing piston, said sealing pistonco-acting with the peripheral wall of said casing, said pressure chamberbeing in communication with an internal pressure of the compressor.

17. Rotary compressor comprising a casing, a rotor within said casing,said rotor cooperating with the inner peripheral wall of said casing andwith suitable end wall structure including a head of the casing, to formsuction and compression chambers, including a sealing member forming anend wall for at least one side of said suction and compression chambers,making endwise contact with said rotor whereby the area of said end 2wall exposed to pressure within said chambers is less than the entirearea of the outer side 0! said end wall, means between said head and endwall for pressing the latter against said rotor by externally appliedfluid pressures, derived from pressures within said compressor, saidmeans being constructed to restrict the application oi. said derivedpressures to localized areas on the outer side of said end wall, saidmeans comprising pisions hermetically fitting recesses formed in thehead or sealing ring, the bottoms of said pistons occluding the opensides of said recesses and contacting the surfaces of the adjacentmember which delineate the said localized areas, being biasedthereagainst by said derived pressures, the extent of said areas beingsufliciently less than the entire area of the entire outer wall or saidsealing means to avoid excessive sealing pressure, but beingsufliciently great to oppose predominant pressure to the pressure withinsaid chambers.

CECIL J. BEUST.

